eth0 drops periodically

My continuing efforts ...

My AMD500 RH7.3 with 2 NICs is connecting on my external NIC (eth0) but
only for a 10minute or so time frame. I then have to ifdown/ifup eth0 to
get it back on the internet. Using qwest. I don't have that problem on
my laptop. I didn't have it before when I had Mandrake. Anyone have an
idea?